Refactor the LN backend and add more logs

backend/src/database.ts

@@ -1,7 +1,7 @@
 import config from './config';
 import { createPool, Pool, PoolConnection } from 'mysql2/promise';
 import logger from './logger';
-import { PoolOptions } from 'mysql2/typings/mysql';
+import { FieldPacket, OkPacket, PoolOptions, ResultSetHeader, RowDataPacket } from 'mysql2/typings/mysql';
 
  class DB {
   constructor() {
@@ -28,7 +28,9 @@ import { PoolOptions } from 'mysql2/typings/mysql';
     }
   }
 
-  public async query(query, params?) {
+  public async query<T extends RowDataPacket[][] | RowDataPacket[] | OkPacket |
+    OkPacket[] | ResultSetHeader>(query, params?): Promise<[T, FieldPacket[]]>
+  {
     this.checkDBFlag();
     const pool = await this.getPool();
     return pool.query(query, params);